• Journal of Periodontal and Implant Science
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• v.37 no.4
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• pp.825-838
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• 2007

Endosseous implants are used in the treatment of various types of tooth loss, and numerous long-term studies have demonstrated the excellent reliability of this method of treatment. However, the increase of implant failure are associated with inadequate quality and/or height of bone. At the end of the 1980s, Wide(>3.75mm) implants were initially used for managing these difficult bone situations. The recommended indications for its use included poor bone quality, inadequate bone height. immediate placement in fresh extraction sockets, and immediate replacement of failed implants. At the 2000s, wider implants(6.0mm and 6.5mm) were used in a few studies. Although good clinical outcomes have been reported in recent years, there is still a controversy on this topic. Therefore, the purpose of this study was to estimate the survival rate of wide implants($6.0{\sim}8.0mm$) in molar regions, evaluating the clinical outcome. In this study, 1135 RBM surfaced wide implants($Rescue^{TM}$, MEGAZEN Co., Korea/595 maxillary, 540 mandibular) were placed in 650 patients(403 male, 247 female/age mean: $51.2{\pm}11.1$ years, range 20 to 83 years). Of the total, 68.3% were used to treat fully or partially edentulous situations, including single-tooth losses and 31.7% were placed immediately after teeth extraction or removal of failed implants, of which all were in the molar regions. Implant diameter and length ranged from 6.0 to 8.0mm and from 5.0 to 10.0mm respectively. The implants were followed for up to 42 months (mean: $14.6{\pm}9.5$ months). Of 1135 placed implants, 58 implants were lost. Among them, 53 implants were lost within 12 months after implant placement. The survival rate was 93.6% in the maxilla and 96.3% in the mandible, yielding an overall survival rate of 94.9%, for up to 42 months. As the result of Cox regression model, prosthetic type, sinus graft, and patient gender have an statistical significance on the implant survival rate in this study. This study suggests that the use of wide implants($6.0{\sim}8.0mm$) would provide a predictable treatment alternative in posterior areas.

• Journal of Science Education
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• v.42 no.2
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• pp.165-181
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• 2018

This study compares and analyzes the characteristics and effects of various educational contextual variables according to students' achievement level and gender groups based on the results of PISA 2015 science domain. PISA 2015 included additional variables about teaching-learning and affective characteristics in the field of science, because science was the main domain of PISA 2015. The results of the mediation analysis using a multiple group structural equation model showed that the environment and strategy for the teaching and learning had a positive effect on the affective characteristics, and also positively affected science achievement through the mediator of the affective characteristics. Particularly, the environment and strategy for the teaching and learning was the most effective in improving the affective characteristics for the low achievement group. It was found that the difference of the mediated effect between achievement level groups was statistically significant, but that between male and female students was not. Therefore, the appropriate the environment and strategy for the teaching and learning will need to be emphasized consistently to improve students' cognitive and affective achievement. The implications and suggestions of these results were discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.317-328
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• 2018

The purpose of this study is to examine the effect of the quality of performance on audience satisfaction, and to verify the mediating effect of service value and traditional image in this process. The subjects of this study included 211 male and female adults who experienced the Korean opera performance in Seoul, Korea in October. Collected data was used as a model of path coefficients obtained through analysis of covariance structure and hypothesis test. As a result of verification, program quality, physical environment quality, and quality of the stage performance perceived by the audience showed a statistically significant positive correlation with performance experience attributes. The path coefficient between performance attribute and service value, performance experience attribute and traditional image were also positively and statistically significant. Further, the path coefficient between performance experience and audience satisfaction showed a positive relationship. The service value and traditional image, service value and audience satisfaction, and the path coefficient between traditional image and audience satisfaction were statistically and positively significant. Finally, all hypotheses were adopted and study results confirmed the effect of service quality and experience attributes on audience satisfaction for the popularization, modernization and marketing strategy of the Korean opera. In this process, it is meaningful to verify the role and function of service value and traditional image.

• The Journal of the Korea Contents Association
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• v.19 no.2
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• pp.340-348
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• 2019

This study analyzes the factors that influence commercial gentrification in Seoul by using both logit model analysis and machine learning with data cumulated from 2015 to 2018 regarding 158 market areas. Logit analysis indicates that log(market area average monthly rent) and the ratio of the purchasing amount by customers aged 40 and younger to total sales in the restaurant and retail business category are statistically significant at 1%; the increase in sales per female customer aged between 30 and 39 in the restaurant and retail business category is statistically significant at 5%; and the increase in number of retailers with a business history of less than two years in the franchise business category is significant at 10%. Machine learning indicates that significant factors ordered by importance are the total retail area, the existence of an industrial complex within the market area, the existence of a traditional market within the market area, the location of subway stations within the market area, the increase of entertainment facilities such as movie theaters within the market area, average monthly rent, and the growth rate of average monthly rent. The contribution of this research is threefold. First, this study analyzes the entire commercial area of Seoul, Korea. Second, this study provides a foundation for future research on predictive indicators by empirically investigating the factors that influence commercial gentrification in Seoul. Lastly, this study introduces various methods of research by utilizing a machine learning approach.

• Journal of Korea Port Economic Association
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• v.35 no.1
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• pp.57-76
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• 2019

This study deals with the determinants of employment productivity of transportation labor, who are the main agents of the transportation industry that has made significant contributions to our country's industrial development. The study selected the determinants of employment productivity using the Korea Labor and Income Panel Study data, and analyzed the effects of various factors using panel logistic regression, panel OLS model, and panel robust regression. The results were as follows. First, a more positive effect was shown when employees held a regular job, had a "high level of education", "joining the labor union" and "experiencing vocational training". Second, in the case of job security, having a "high level of education" and "joining the labor union" showed a more positive effect; further, job security was higher for employees who worked in a "big company" or were "married". Third, in the case of higher income productivity, higher values of "age", "academic ability" and "company size" had a more positive effect, whereas larger values of "education" and "health condition except job training" had a negative one. Fourth, in the case of job satisfaction, "female", "joining the labor union" and having a higher "income" or "job security" led to higher satisfaction and a better "health condition compared to an average person". Further, a higher "overall life satisfaction" and "economic level" led to lower job satisfaction. The analysis of the determinants of employment productivity of transportation business and seeking for improvement plan is expected to improve the employment productivity in the transportation business.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.5
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• pp.64-78
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• 2019

This paper explores key factors affecting taxi travel using global positioning system(GPS) data in Seoul, Korea, considering spatial dependence. We first analyzed the travel characteristics of taxis such as average travel time, average travel distance, and spatial distribution of taxi trips according to the time of the day and the day of the week. As a result, it is found that the most taxi trips were generated during the morning peak time (8 a.m. to 9 a.m.) and after the midnight (until 1 a.m.) on weekdays. The average travel distance and travel time for taxi trips were 5.9 km and 13 minutes, respectively. This implies that taxis are mainly used for short-distance travel and as an alternative to public transit after midnight in a large city. In addition, we identified that taxi trips were spatially correlated at the traffic analysis zone(TAZ) level through the Moran's I test. Thus, spatial regression models (spatial-lagged and spatial-error models) for taxi trips were developed, accounting for socio-demographics (such as the number of households, the number of elderly people, female ratio to the total population, and the number of vehicles), transportation services (such as the number of subway stations and bus stops), and land-use characteristics (such as population density, employment density, and residential areas) as explanatory variables. The model results indicate that these variables are significantly associated with taxi trips.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.6
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• pp.67-77
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• 2018

Currently, there are many problems due to the decline in school-age population. Moreover, Korea has the largest number of universities compared to the population, and the university enrollment rate is also the highest in the world. As a result, the minimum student retention rate required for the survival of each university is becoming increasingly important. The purpose of this study was to examine the effects of reducing the number of graduates of education and the social climate that prioritizes employment. And to determine what the basic direction is for students to manage the student retention rate, which can be maintained from admission to graduation, to determine the optimal input variables, Based on the input parameters, we will make associative analysis using apriori algorithm to collect training data that is most suitable for maintenance rate management and make base data for development of the most efficient Deep Learning module based on it. The accuracy of Deep Learning was 75%, which is a measure of graduation using decision trees. In decision tree, factors that determine whether to graduate are graduated from general high school and students who are female and high in residence in urban area have high probability of graduation. As a result, the Deep Learning module developed rather than the decision tree was identified as a model for evaluating the graduation of students more efficiently.

• Clinical and Experimental Reproductive Medicine
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• v.21 no.2
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• pp.183-190
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• 1994

Purpose of the present study was to find the optimal culture conditions for the maturation and fertilization of immature oocytes by the use human body fluids and gonadotropins (Gn) in the mouse model. Cumulus-enclosed mouse immature oocytes were incubated in the medium containing various human body fluids with or without Gn in vitro, and examined to confirm nuclear maturation (NM) and fertilization. Female ICR mice were stimulated with 7.5 IU pregnant mares' serum gonadotropin (PMSG). Cumulus-enclosed immature oocytes were isolated at 48-52 hr post PMSG injection and cultured in TCM 199 supplemented with various concentrations (20, 50, and 70%) of human body fluids such as fetal cord serum (hCS), follicular fluid (hFF), peritoneal fluid (hPF) and amniotic fluid (hAF) in the presence or absence of 10 IU/ml PMSG and 10 IU/ml human chorionic gonadotropin (hCG) for 18 hr. Fetal calf serum (FCS) was used as a control for the supplements. Matured oocytes were fertilized with sperm collected from the epididymis of male mice. Fertilization was conducted in T6 medium containing 15 mgl ml bovine serum albumin, and confirmed at 6 hr post-insemination. Evaluation of nucler maturation and fertilization was carried out by rapid staining using fuchin. There was no significant difference between the effects of human body fluids and FCS supplements on nuclear maturation of cumulus enclosed mouse immature oocytes. When maturation medium was supplemented with 20% hPF or 20% hAF, fertilization rates were significantly (P<0.01) lower than that of 20% FCS, hCS and hFF groups. However, higher concentrations of body fluids during IVM were not more beneficial on fertilizability of oocytes. The addition of Gn significantly increased the fertilization rates in hPF and hAF groups (hPF without Gn; 51.5%, compared with 85.1% for addition of Gn, and hAF without Gn; 30.1% compared with 85.8% for addition of Gn) at 20% concentration. These results suggest that human body fluids at 20% concentration and gonadotropins can be used as supplements for the maturation of mouse immature oocytes in vitro. When gonadotropins supplemented with the human body fluids in the maturation medium, fertilizability of mouse immature oocytes was increased in hPF and hAF groups. These results can be applied to maturation of human immature oocytes in vitro.

• Korea journal of population studies
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• v.23 no.2
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• pp.143-166
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• 2000

This paper attempts to explore the relation between health care availability and child mortality among ethnic groups with different cultural traditions of sex preference. Micro-data from the 1990 Census of China for Yanbian and Xishuangbanna Prefectures are used. Based on the analysis of data for Koreans, Hans, and Dais in these prefectures, a new model explaining the relation between sex preference, health care. and differentials in child mortality is proposed in this paper. In societies, where health care is easily available, the level of child mortality is not likely to be a function of sex preference. In societies where there is little availability of health care, members of ethnic groups with strong sex preference do whatever possible to assure survival of their children of the preferred sex. But actions to assure survival of children of the sex not preferred by their parents depend on the costs involved and other considerations. Therefore, the level of child mortality for the preferred sex is likely to be substantially lower than that of the not-preferred sex. However, as availability of health care improves and the cost of obtaining health care becomes lower, survival of children of the not-preferred sex are likely to improve. It is generally agreed that Koreans and Hans show strong son preference, while Dais have cultural traditions of daughter preference. In Yanbian, where virtually all children receive health care whenever it is needed, Korean females and Han females show lower child mortality than their male counterparts, although the difference is not found to be significant for Koreans. In Xishuangbanna, where there is little availability of health care, Dai males show markedly higher child mortality than Dai females, and Han females have higher child mortality than Han males. However, small improvements in the availability of health care in Xishuangbanna translate into substantial improvements in survival of male children for Dais, and survival of female children for Hans.

• Journal of Labour Economics
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• v.26 no.3
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• pp.149-179
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• 2003

This study is analysing the factors determining individuals' behavior of selecting self-employment not only at the micro-level but also at the macro-level to put a particular emphasis on the financial constraint and unemployment rate representing business cycle. The data used in this study are "Korean Labor and Income Panal Study" of the Korea Labor Institute and "Economically Active Population Survey" of National Statistical Office. The main findings are as follows. First, human capital such as educational attainment and job experience has positive effects on male's selection of self-employment. The effects of job experience, however, changed negative for female's selection of self-employment. Second, real estate is significantly enhancing the selection probabilities of employer selection while the income from financial assets has negative effects. Third, entrepreneurial culture and environment are also raising the self-employment selection probability. Lastly, the regional unemployment rate representing the business cycle has positive effects on the self-employment selection after the financial crisis in 1997 both at the micro and macro level. Moreover, the coefficient of regional unemployment rate has changed positive in the structural model of self-employment selection controlling for selection bias and income opportunities, which means that individual's behavior of self-employment selection is rather complex when accounting for the uncertainties of income opportunities and diverse characteristics of self-employment workforce.